In general, an aqueous solution such as nutritional supplement, distilled water, and the like, including physiological salt solution and glucose is stored in an aqueous-solution pack having a certain shape in hospitals, etc., where a medical treatment or a surgical operation is performed on a patient. In addition, the infusion port is engaged with an inlet port connected to a lower end of the aqueous-solution pack, and a ringer spike is inserted into a sealing cap disposed at a lower end of the infusion port in order to supply the aqueous solution to the patient so that the aqueous solution can be administered to the patient. A conventional infusion port entails a problem in that the sealing cap is formed of a rubber material, which contributes to an increase in the overall expense incurred to manufacture the infusion port due to a high unit price. Moreover, when the ringer spike is inserted into the sealing cap, it is torn to create rubber fragments, which may be in turn introduced into the infusion port. Thus, since noxious substances harmful to the human body are produced from the rubber fragments of the sealing cap, they may be mixed with the aqueous solution. Further, the noxious substances mixed with the aqueous solution may be administered to the patient due to leakage of an additive added to the sealing cap during the manufacture of the sealing cap of a rubber material, leading to a serious deterioration in safety of the patient.